The union said 115,000 postal workers “have urged Royal Mail bosses to ‘take stock’ and change course in negotiations” following the result of the ballot, announced yesterday (16 February).

Despite the intensity of the dispute and employees retiring or leaving the company, the CWU said turnout rose from the two previous ballots, which were 77% and 72.2% respectively.

This, it added, makes this vote the biggest mandate for strike action since the implementation of the 2016 Trade Union Act.

CWU general secretary Dave Ward said: “After two national ballots, 18 days of action, constant management intimidation and scores of unjust disciplinary cases against their colleagues, postal workers have shown their dignity and determination once again.

“This vote is a historic testament to CWU members across the country who have stood firm against the most severe attacks faced by any set of workers since the miners.

“It is proof that postal workers will not accept their livelihoods being destroyed so that a few at the top can generate serious profits at their expense.

“It is proof that workers loyal to an historic institution like Royal Mail will not accept it being turned into an Uber-style, bog-standard gig economy employer.

“It is proof that for Royal Mail to begin functioning normally again, there needs to be a change in negotiating approach from its leadership that recognises the depth of feeling from the workforce that make their company.”

He added: “These people will never be bullied, intimidated or harassed into submission, and this result is a concrete demonstration of that spirit.

“I urge responsible voices in Royal Mail’s leadership to take stock of what has happened today.”

In a statement posted on its website in response to the vote, Royal Mail said: “We are disappointed that the CWU members who took part in the ballot have voted in favour of taking further industrial action."

The postal operator said it remained "committed to resolving this dispute and want to agree a pay and change deal for our people".

“The CWU have not announced any dates for further strike action to take place.

“In the event the CWU do announce further strike action, we have plans to minimise disruption and get our services back to normal as soon as possible after strike action to keep people, businesses and the country connected.

“We remain committed to getting around the table with the CWU, resolving this dispute and agreeing a pay and change deal for our people. That is in the best interests of customers, Royal Mail, and its employees.”

Royal Mail believes the 18 days of strike action that took place last year will cost the business around £200m.